His code name is Sparrow. During revolutionary times in 1940s Shanghai, Chen Shen (Li Yi Feng) is a secret double agent who works in the Special Operations Division of the Reorganized National Government of China. His mission is to gather intelligence about the Japanese “Return to Zero” program for the Communist Party.

Bi Zhong Liang (Zhang Lu Yi) is Chen Shen’s supervisor who regards him like a brother because Chen Shen saved his life in the past. However, Zhong Liang begins to suspect Chen Shen’s actions and sets out traps to expose his true intentions.